Topic
Parabolic reflector
About: Parabolic reflector is a research topic. Over the lifetime, 3375 publications have been published within this topic receiving 30735 citations. The topic is also known as: paraboloid reflector & paraboloidal reflector.
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TL;DR: The feasibility of using null screens for testing the segments of a parabolic segmented telescope mirror for the Large Millimeter Telescope (LMT) is analyzed and an algorithm for designing the null screen forTesting the off-axis segments of conic surfaces is described.
Abstract: The feasibility of using null screens for testing the segments of a
parabolic segmented telescope mirror for the Large Millimeter Telescope
(LMT) is analyzed. An algorithm for designing the null screen
for testing the off-axis segments of conic surfaces is
described. Actual screen designs for the different classes of
segments of the LMT are presented. The sensitivity of the test and
the required accuracies for the fabrication and positioning of the
screen are analyzed. A measuring accuracy of ∼12 µm in
surface sagitta is within the reach of the technique.
42 citations
TL;DR: In this article, a closed-form analytical solution is developed for predicting the early-time transient electromagnetic fields which are generated by a perfectly conducting parabolic reflector antenna when it is illuminated by a transient step spherical wave due to an elemental Huygen's source located at the focus.
Abstract: A closed-form analytical solution is developed for predicting the early-time transient electromagnetic fields which are generated by a perfectly conducting parabolic reflector antenna when it is illuminated by a transient step spherical wave due to an elemental Huygen's source located at the focus. This closed-form time-domain solution, which is valid both near and far from the reflector (and anywhere in the forward region) can be used via the convolution theorem to efficiently obtain the early-time transient fields generated by the same parabolic reflector antenna when it is illuminated by a realistic finite-energy pulse which emanates as a spherical wave from the focus. The transient solution is developed here by analytically inverting, in closed form, the corresponding frequency-domain solution in terms of a radiation integral that employs an asymptotic high-frequency geometrical optics (GO)-based approximation for the fields in the aperture. Numerical results are presented for the transient fields both near and far from the reflector. The fields on boresight exhibit an impulse-like behavior similar to that of the impulse radiating antenna (IRA) introduced by Baum et al. (1989, 1993).
42 citations
TL;DR: A device that maximizes the probability of collecting all of the scattered and ballistic light isotropically generated at the focal spot of multiphoton excited emissions (MPE) to optimize the signal‐to‐noise ratio (SNR) for micro‐imaging is constructed.
Abstract: Summary
We have constructed a device that maximizes the probability of collecting all of the scattered and ballistic light isotropically generated at the focal spot of multiphoton excited emissions (MPE) to optimize the signal-to-noise ratio (SNR) for micro-imaging. This was accomplished by optically coupling a parabolic reflector (that surrounds the sample and top of the objective) to a pair of collimating lenses (above the sample) that redirects emitted light to a separate detector. These additional optics, combined with the objective, allow the total emission detection (TED) condition to be approached. Numerical simulations suggest an approximately 10-fold improvement in SNR with TED. Comparisons between the objective detection and TED reveal an enhancement of 8.9 in SNR (77% of predicted) for GFP-labelled brain slices and similar results for fluorescent beads. This increase in SNR can be used to improve time resolution, reduce laser power requirements/photodynamic damage, and, in certain cases, detection depth, for MPE imaging techniques.
42 citations
Patent•
27 Sep 1993
TL;DR: In this paper, an ultraviolet (UV) sterilization system for food cartons is described, where a parabolic cylinder reflector is mounted in a housing with the focus of the reflector coinciding with the axis of the arc in the UV lamp.
Abstract: An ultraviolet (UV) sterilization system for food cartons is disclosed. An elongated UV lamp is mounted in a housing. A parabolic cylinder reflector is mounted in the housing with the focus of the reflector coinciding with the axis of the arc in the UV lamp. The shape of the parabolic reflector directs radiation from the lamp into cartons positioned on a conveyor below the lamp. The axis of the arc is parallel to the direction of movement of the cartons on the conveyor. The front surface of the reflector also absorbs heat from the lamp and heat is removed from the reflector by circulating air over the back surface of the reflector.
42 citations
TL;DR: In this article, the geometric characteristics of conic-section-generated offset reflectors are studied in a unified fashion and some unique geometrical features of reflector rim constructed from the intersection of the reflector surface and a cone or cylinder are explored in detail.
Abstract: Geometrical characteristics of conic-section-generated offset reflectors are studied in a unified fashion. Some unique geometrical features of the reflector rim constructed from the intersection of the reflector surface and a cone or cylinder are explored in detail. It is found that the intersection curve (rim) of the rotationally generated conic-section reflector surface and a circular cone with its tip at the focal point is always a planar curve and has a circular projection on the focal plane only for the offset parabolic reflector. Furthermore, in this case, the line going through the center of the circle, parallel to the focal axis, and the central axis of the cone do not intersect the reflector surface at the same point. Numerical results are presented to demonstrate some unique features of offset parabolic reflectors.
42 citations